Using laptop with external monitor only

  • Hi there and welcome to PC Help Forum (PCHF), a more effective way to get the Tech Support you need!
    We have Experts in all areas of Tech, including Malware Removal, Crash Fixing and BSOD's , Microsoft Windows, Computer DIY and PC Hardware, Networking, Gaming, Tablets and iPads, General and Specific Software Support and so much more.

    Why not Click Here To Sign Up and start enjoying great FREE Tech Support.

    This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.
Welcome to our Community
Wanting to join the rest of our members? Feel free to sign up today.
Sign up
Status
Not open for further replies.

seskanda

PCHF Member
PCHF Member
Dec 30, 2019
11
0
33
Hello

I have a Dell Vostro 3450 and the internal LCD screen has failed. I can hook it up via blue 15-pin VGA port to an external monitor, but I'm just able to go into the BIOS screen. When I try to boot up into Windows I get eight beeps followed by a black screen. Is any way to get it to work on external monitor without the internal LCD screen?

Thanks in advance
 

Rustys

Escaped Mental Patient
Administrator
Support Team
Jul 22, 2016
2,225
627
127.0.0.1
pchelpforum.net
If the system is still under any type of warranty would file a claim. This could also be caused by the motherboard failure.
Could be a loose cable form the LCD to the motherboard.
Have you attempted the LCD test

To run the Built-In Self-Test perform the following:
  • Turn the computer off.
  • Press and hold the D key while pressing the power button. This will start the BIST.
  • The screen will display multiple flashing colors. Look for lines, distortion, or any other video issues you have observed.
  • The laptop will restart when the test is finished.

If no video is shown yet at this point it is recommended to connect the computer to an external monitor (if available) to confirm if video problem is related to the LCD panel or to the computer’s video card itself.

It has also been suggested to clear the power and try removing the CMOS battery.
 

seskanda

PCHF Member
PCHF Member
Dec 30, 2019
11
0
33
Appreciate the help yet so far nothing works. I forgot to mention that I also tried using the HDMI port to my TV, but I had the same results as with the VGA port. Will have to wait until Monday and try the USB to VGA adapter. I got a USB to HDMI VGA adapter as well. It is similar to the one below:


I did the BIST but the screen is just blank, however as stated in original post it works fine when connected to external monitor via VGA port, but can only go into the BIOS after that I get eight beeps and black screen too.
 

seskanda

PCHF Member
PCHF Member
Dec 30, 2019
11
0
33
I just got the usb adapter and that does not work at all. Cannot even get into the BIOS, pretty sure these things need an OS. I think since the flex cable for internal screen is disconnected that is what causes the eight beeps. Unfortunately, that cable is broken and do not have another to try, but that is last option for me. Unless someone else knows what else to do.
 

Rustys

Escaped Mental Patient
Administrator
Support Team
Jul 22, 2016
2,225
627
127.0.0.1
pchelpforum.net
Replace the flex cable which may not fix the issue.
It may be the LED screen that is the issue and or some other piece of hardware.
 

phillpower2

Autonomous Admin
Administrator
Support Team
Sep 9, 2016
5,238
583
56
I think since the flex cable for internal screen is disconnected that is what causes the eight beeps. Unfortunately, that cable is broken and do not have another to try,
If you are getting eight beeps after having pressed the Fn and the F8 keys to toggle between displays then you are correct and the MBs video to screen ribbon needs to be replaced, the eight beeps is the Dell BIOS telling you that the power on self test has failed, replacement part here
 

seskanda

PCHF Member
PCHF Member
Dec 30, 2019
11
0
33
I really do not know what else the issue could be if not the flex cable or LCD screen itself
If you are getting eight beeps after having pressed the Fn and the F8 keys to toggle between displays then you are correct and the MBs video to screen ribbon needs to be replaced, the eight beeps is the Dell BIOS telling you that the power on self test has failed, replacement part here
I will find one of these LCD flex cables online and see if that fixes it.
 

phillpower2

Autonomous Admin
Administrator
Support Team
Sep 9, 2016
5,238
583
56
Can you tell us how you initiated the LCD BIST as in what keys did you use and when did you press them.

The eight beep behaviour that you describe suggests that the video ribbon may have become detached from the motherboard but that would not affect you being able to run the Dell LCD BIST, if the test was initiated correctly it would suggest that there are two problems, bad screen and bad/disconnected video ribbon.

DELL VOSTRO 3450 DISASSEMBLY
 

seskanda

PCHF Member
PCHF Member
Dec 30, 2019
11
0
33
I did LCD BIST using the exact same instructions as mentioned in the above post, that is, holding the D key while turning laptop on.

I ran the LCD BIST on an external monitor not the internal one and the flex cable was disconnected as I threw it away since it does not work, also still waiting on that lcd flex cable to arrive, but if I plug that in and it works on external monitor without internal one I will be surprised, because it seems the BIOS does the eight beeps to prevent external monitor to work if the internal is not working.
 

phillpower2

Autonomous Admin
Administrator
Support Team
Sep 9, 2016
5,238
583
56
Will address things one at a time but you need to be made aware of certain important information.

I ran the LCD BIST on an external monitor not the internal one and the flex cable was disconnected as I threw it away since it does not work,
You cannot run the LCD BIST on a non Dell monitor as the function is specific to Dell screens and not even all Dell screens have the function built in, the LCD BIST allows for the screen to self test and, if you run the LCD BIST on this Vostro 3450 notebook and you get nothing on the display the panel needs to be replaced.

It may have been nothing to do with the video cable but regardless of this if no cable connection is detected when the BIOS carries out the power on self test (POST) you will get these eight beeps as the lack of cable connection is detected as a fault by the BIOS.

The crux of it is, you cannot do anything without a fully functional video ribbon that is specific to your Dell Vostro 3450 notebook.
 

seskanda

PCHF Member
PCHF Member
Dec 30, 2019
11
0
33
You cannot run the LCD BIST on a non Dell monitor as the function is specific to Dell screens and not even all Dell screens have the function built in, the LCD BIST allows for the screen to self test and, if you run the LCD BIST on this Vostro 3450 notebook and you get nothing on the display the panel needs to be replaced.

It may have been nothing to do with the video cable but regardless of this if no cable connection is detected when the BIOS carries out the power on self test (POST) you will get these eight beeps as the lack of cable connection is detected as a fault by the BIOS.

The crux of it is, you cannot do anything without a fully functional video ribbon that is specific to your Dell Vostro 3450 notebook.
It turns out I mistakenly ran the BIST on another Dell laptop I have and not the Vostro 3450. I know the BIST only works on the internal screens of laptops. But, in my case, the BIST will not show anything at all. Of course, that can only mean it is dead. But the fact the external monitor works tells me the video card is fine and only internal screen is bad.

So if I simply connect a good, known, LCD flex cable and no screen at all then that should bypass the eight beeps, then? I hope that is the trick, still have to wait until Thursday to get it.

I hope all I need is this LCD flex cable and not an internal screen too just for the external monitor to work
 

phillpower2

Autonomous Admin
Administrator
Support Team
Sep 9, 2016
5,238
583
56
It turns out I mistakenly ran the BIST on another Dell laptop I have and not the Vostro 3450.
Wow, how on earth did you manage to that :unsure:

But the fact the external monitor works tells me the video card is fine and only internal screen is bad.
I`m not convinced of this tbh and have my fingers crossed for you that it is just the missing video ribbon that is stopping you being able to use just an external display, the BIOS on OEM brand computers are notoriously picky and it is a toss up between Dell and HP who is the worst.

You need to connect the video ribbon to both the motherboard and the screen regardless of the fact that the screen does not work.
 

seskanda

PCHF Member
PCHF Member
Dec 30, 2019
11
0
33
Wow, how on earth did you manage to that :unsure:
It was a mistake Dell makes too many laptops that look alike :)

I`m not convinced of this tbh and have my fingers crossed for you that it is just the missing video ribbon that is stopping you being able to use just an external display, the BIOS on OEM brand computers are notoriously picky and it is a toss up between Dell and HP who is the worst.

You need to connect the video ribbon to both the motherboard and the screen regardless of the fact that the screen does not work.
I sure hope that is the case still have to wait until tomorrow to get the LCD cable. I think the BIOS wants an internal screen present even when external display is already connected and we try to trick it by only connecting the LCD flex cable. I prefer Dell BIOS over HP since HP rarely if ever boots from SD card reader but that is another topic.

Well that beats the whole purpose of this thread which is just using the LCD flex cable and external monitor.
 

phillpower2

Autonomous Admin
Administrator
Support Team
Sep 9, 2016
5,238
583
56
Yep I second HP BIOS being a pain in the proverbial, especially for folks who want to upgrade the add on GPU.

What was the damage to the original video ribbon, it must of been bad *perhaps even snapped) for you to get the eight beeps when the the ribbon was attached to both the MB and screen.
 

seskanda

PCHF Member
PCHF Member
Dec 30, 2019
11
0
33
Of course I've seen much worse than HP BIOSes also but again that is for another thread topic

Not sure but maybe I tear it somehow I never tried attaching the cable and screen yet. Well I finally got the LCD flex cable and as expected that does not get me around the eight beeps, unless I go into BIOS. If anyone knows how to use external monitor only and not have internal screen attached let me know.
 

phillpower2

Autonomous Admin
Administrator
Support Team
Sep 9, 2016
5,238
583
56
Will connecting the notebook to an external screen allow you to run the Dell diagnostics for the rest of the hardware, continually tapping F12 when restarting the notebook should be the "how to" for your notebook.

If anyone knows how to use external monitor only and not have internal screen attached let me know.
Seen this done a few times but honestly can`t recall if any were a Dell and am pretty sure that you can`t with a Dell, I did mention in my reply #14 that I wasn`t convinced that the screen or ribbon was the only problem and sorry to say that you now having connected a known good video ribbon more or less confirms it.
 

seskanda

PCHF Member
PCHF Member
Dec 30, 2019
11
0
33
I may be able to get into diagnostics but what is it that I should run a diagnosis of ? The LCD screen is not working or connected. And I if do a full scan that will take hours especially the memory tests.

Seen this done a few times but honestly can`t recall if any were a Dell and am pretty sure that you can`t with a Dell, I did mention in my reply #14 that I wasn`t convinced that the screen or ribbon was the only problem and sorry to say that you now having connected a known good video ribbon more or less confirms it.
I bet in older laptops the BIOS allowed to use external screen without having an internal one connected. Yes I made the assumption that the missing LCD flex cable caused it to do the eight beeps, but was wrong about that. Now, I think it is because the LCD screen is not connected. But it will probably still do eight beeps as the internal screen is bad.
 

phillpower2

Autonomous Admin
Administrator
Support Team
Sep 9, 2016
5,238
583
56
Entirely up to you if you see if you are able to run any suggested tests but what have you got to lose, the notebook atm is nothing more than a thorn in your side.

If you are able to run the tests via an external screen you should test everything that you can, as said above you have nothing to lose by doing so.

Yes I made the assumption that the missing LCD flex cable caused it to do the eight beeps, but was wrong about that. Now, I think it is because the LCD screen is not connected
Can I ask what you mean by the LCD screen is not connected.
 
Status
Not open for further replies.